Skeletal animation for multiple meshes
Every animation you do will create a - so called - "action" which is a datablock that can be transfered to any other rig. All the bones involved must share exactly the same names.

To understand the thing, try create a simple rig from scratch, parent it with a simple mesh, Shift D duplicate both object and armature and move the new obj-rig away from the original position.

create an animation of the first rig-object;
select the second rig, go to pose mode, open a dope-sheet window, in the header change the drop down menu from "dopesheet" to "action"; change the dropdown menu from "new" (2nd rig has no actions, by now) to the only one you have created.

Now, moving the timeline, both objects move together, as they share the same action and the same bone names.

Note that the action is referred to the local space of the object, so, if the 2 object have different positions, they will move as twins, in their respective position.

The same you can apply with complex models and rigs, if they share the same bone names.